CN1867135A - Method for positioning user terminal and user terminal - Google Patents

Abstract

The present invention provides a method for locating a user terminal and the user terminal. The method mainly includes: the user terminal obtains and saves distance information between base stations in a cell and adjacent cells; the user terminal is in the IDLE (idle) state , measure the synchronization channels of the resident cell and the neighboring cell, obtain the distance change information between the resident cell and the base station of the neighboring cell, and determine the location range of the user terminal according to the stored distance information and the measured distance change information . By using the method of the invention, it is possible to accurately locate the user terminal when the user terminal is in the IDLE state.

Description

Method for locating user terminal and user terminal

technical field

The present invention relates to the communication field, in particular to a method for locating a user terminal and the user terminal.

Background technique

GSM (Globe System of Mobile Communication) and GT800 (800M frequency band) trunking communication based on GSM have high requirements for user positioning.

Taking the mobile phone as an example, the measurement process of the user terminal is described below.

In the process of turning on the Internet or reselecting the cell, the mobile phone of the user will first obtain the FCCH (Frequency Correction Channel), use the FCCH to correct the frequency, and then synchronize the base station according to the synchronization sequence contained in the SCH (Synchronization Channel). After the mobile phone and the base station are synchronized and the system information is obtained, the mobile phone can reside in the base station. At this time, there is no distance parameter between the mobile phone and the base station.

Then, the mobile phone performs the location update process or the dedicated channel occupation process, and interacts with the base station to obtain the distance information TA (time advance) between the mobile phone and the base station. The corresponding relationship between TA and the mobile phone air interface BIT (binary number) is, 1 BIT3.69us, about 550m.

After the dedicated channel is occupied, the mobile phone will be in the IDLE (idle) state. At this time, the mobile phone will not obtain the TA value notified by the base station during the movement process. The mobile phone synchronizes the BCCH (broadcast control channel) channel of the base station in real time to ensure that synchronization.

When the mobile phone is in the IDLE state and the dedicated channel state, it is measuring the level of the adjacent cell in real time for handover and cell reselection. The specific measurement process is: the mobile phone obtains the frequency point information of the adjacent cell to be measured through the system message, and then the mobile phone tunes to the frequency point to obtain the BCCH level, and synchronizes the SCH (synchronization channel) to obtain the BSIC (base station color code) of the cell . Finally, the measured adjacent cells are arranged according to the level of the BCCH. When performing handover and cell reselection, select as required.

At present, the positioning technologies in GSM and GT800 mainly include: GPS (Global Positioning System), AGPS (Assisted GPS Positioning), E-OTD (Enhanced Observation Time Difference Positioning), CELLID (Cell Identification), CELLID+TA (Cell Identification Combined with Time Advance) and CELLID+TA+RX (cell identification combined with timing advance and receiving level), etc.

The various positioning technologies mentioned above can be divided into two implementation modes that need to add external devices and those that do not need to increase external devices.

The first implementation method requires the positioning method of external equipment, and the positioning method includes the following positioning technology:

GPS positioning. This positioning method requires that the terminal of the user terminal is equipped with a GPS receiver for receiving GPS satellite signals. Due to the shielding effect of buildings, it is generally difficult to receive GPS signals indoors, so GPS positioning is not suitable for indoor positioning. Since this positioning method requires the terminal to add a GPS receiver, the size of the terminal increases and the cost increases.

A-GPS positioning. This positioning method performs GPS positioning with network assistance, which can save positioning time, but also has the above-mentioned problems of GPS positioning.

E-OTD positioning. This positioning method requires the synchronization of the entire network or adding a positioning network element on the base station side, which is costly and inconvenient to maintain.

Although the above three positioning methods that require additional equipment have high positioning accuracy, they cannot be received in buildings due to the sensitivity of the GPS receiver. The positioning speed is slow and the equipment is expensive. The terminal needs to add a GPS receiving device, and when the software needs to be modified, both the network side and the terminal side need to be modified.

The second main method does not need to add external equipment, and uses a positioning method of network resources. The positioning method includes positioning technologies such as CELLID, CELLID+TA, and CELLID+TA+RX.

The positioning methods mentioned above do not need to add external devices, and the positioning accuracy is limited. Among them, the RX measurement is greatly affected by the environment, and cannot be accurately correlated with the distance, resulting in a large error. The advantage of this positioning method is that when the software needs to be modified, no modification is required on the terminal side.

In a word, it is difficult for the above-mentioned existing positioning methods to realize cheap, fast and accurate positioning of the user terminal, and the network resources are not fully utilized.

Contents of the invention

In view of the above-mentioned problems in the prior art, the purpose of the present invention is to provide a method for locating a user terminal and the user terminal, so that the user terminal can be accurately positioned when the user terminal is in the IDLE state.

The purpose of the present invention is achieved through the following technical solutions:

A user terminal, including: a benchmark information acquisition module, a distance change information acquisition module and a position determination module, wherein:

Benchmark information acquisition module: used to obtain the benchmark information of the residential cell and neighboring cells of the user terminal through the location update process and cell reselection process of the user terminal, and pass the acquired benchmark information to the distance change information acquisition module and location determination module;

Distance change information acquisition module: used to measure the residence cell of the user terminal and the synchronization channel of the neighboring cell when the user terminal is in the idle IDLE state, and calculate the real-time calculation of the user terminal based on the benchmark information transmitted by the benchmark information acquisition module and the distance change information between the base stations of the residential cell and the neighboring cell, and transfer the obtained distance change information to the position determination module;

Position determination module: according to the benchmark information and the distance change information transmitted by the distance change information acquisition module transmitted by the benchmark information acquisition module, determine the current distance between the user terminal and the residential cell and the base station of the neighboring cell, according to the current distance Information and the location information of the residential cell of the user terminal and the adjacent cells, and determine the location range information of the user terminal through calculation.

include:

Positioning channel monitoring module: used to monitor the positioning channels of the cell where the user terminal resides and adjacent cells, obtain the current location information of the cell where the user terminal resides and adjacent cells, and pass the obtained location information to the location determination module.

include:

The benchmark information saving module: used to save the benchmark information acquired by the benchmark information acquisition module, and transmit the saved benchmark information to the position determination module and the distance change information acquisition module.

The described location determination module includes:

Position calculation module: according to the current distance information between the user terminal and the cell where the user terminal resides and the base station in the neighboring cell, as well as the location information of the cell where the user terminal resides and the adjacent cell, calculate the location range information of the user terminal through a set algorithm;

Information feedback module: transmit the obtained current distance information between the user terminal and the cell and each neighboring cell to the benchmark information acquisition module, and the benchmark information acquisition module uses the current distance information as new benchmark information of the cell and each neighboring cell.

The benchmark information includes: the time advance TA value information of the user terminal from the base station of the cell, the cell identifier, the cell distance, and the window position of the cell synchronization channel.

A method for locating a user terminal, comprising:

A. The user terminal obtains and saves and stores the distance information between the cell and the base station of the adjacent cell;

B. When the user terminal is in the idle IDLE state, measure the synchronization channel of the resident cell and the adjacent cell, obtain the distance change information between the resident cell and the base station of the adjacent cell, and change the distance according to the stored distance information and the measurement information to determine the location range of the user terminal.

Described step A specifically comprises:

The user terminal obtains and saves the benchmark information of the cell it resides in and the base station in the neighboring cell. The benchmark information includes: the time advance TA value information of the user terminal from the base station, the cell identifier, the cell distance, and the window of the cell synchronization channel Location.

Described step A specifically comprises:

A1. Add a positioning channel to the trunking communication system;

A2. After the user terminal is turned on, it performs a normal location update process to obtain the benchmark information of the cell where it resides. Then, the user terminal initiates a cell reselection process to obtain the benchmark information of each neighboring cell through the positioning channel.

Described step A2 specifically comprises:

A21. The user terminal obtains the location information of the cell and each neighboring cell including latitude and longitude information through the positioning channel. The user terminal sorts each neighboring cell according to the level of each neighboring cell, and initiates the reselection process of each neighboring cell in turn. , to obtain the positioning channel description of each neighboring cell;

A22. According to the description of the positioning channel, the user terminal enters the positioning channel to send an uplink access calibration request message to the base station of the neighboring cell, receives the calibration information returned by the base station of the neighboring cell through the positioning channel, and obtains the calibration information of the neighboring cell. pole information.

Described step A specifically comprises:

A3. Add system messages in GSM;

A4. After the user terminal is powered on, it performs a normal location update process to obtain the benchmark information of the cell where it resides. Then, the user terminal initiates a cell reselection process, and obtains the benchmark information of each neighboring cell through the system message.

Described step A4 specifically comprises:

A41. The user terminal obtains the location information of the cell and each neighboring cell including latitude and longitude information through system messages, and the user terminal sorts each neighboring cell according to the level of each neighboring cell, and initiates the reselection process of each neighboring cell in turn , to obtain the system information of each neighboring cell;

A42. The user terminal sends an uplink access calibration request message to the neighboring cell base station according to the system message, receives the calibration information returned by the neighboring cell base station, and obtains benchmark information of the neighboring cell.

Also includes:

When the user terminal loses part or all of the benchmark information, the user terminal will re-select the neighboring cell after the power-on process is completed. Benchmark information, for a cell without a TA benchmark, the user terminal reselects the cell according to the signal level, and obtains the benchmark information of the cell.

Described step B specifically comprises:

When the user terminal is in the IDLE state, based on the obtained benchmark information of the local cell and each neighboring cell, real-time calculation of the distance change information ΔTA between the local cell and each neighboring cell base station, according to the ΔTA and the benchmark information , to determine the distance to the base station of the cell and each neighboring cell, and then determine the location range of the user terminal.

Described step B specifically comprises:

B1. When the user terminal is in the IDLE state, the obtained TA of the cell is used as the benchmark. During the movement process, the broadcast control channel BCCH channel of the base station is synchronized, the training sequence is demodulated, and the user terminal and the resident are calculated in real time. The distance change ΔTA of the base station, and then, determine the current distance between the user terminal and the camping base station=TA+ΔTA;

B2. The user terminal detects the level of each neighboring cell in real time, takes the TAn of each neighboring cell as a benchmark, and confirms the deviation between the current synchronization sequence and the benchmark through the synchronization sequence, measures the deviation of the demodulation data, and calculates the user in real time The distance change ΔTAn between the terminal and each neighboring base station, and then determine the current distance between the user terminal and each neighboring base station=TAn+ΔTAn;

B3. The user terminal determines the location range of the user terminal through calculation according to the obtained current distance from the base station of the cell and each neighboring cell, and the location information of the cell and each adjacent cell.

Described step B3 specifically comprises:

According to the current distance between the user terminal and the base station of the cell, the user terminal determines that the user terminal is within a circle with the base station as the center and the minimum radius is the current distance and the width is 550m. For the current distance, it is determined that the user terminal is within the boundary range between circular rings with a minimum radius of the current distance and a width of 550 m centered on each neighboring cell.

Described step B also includes:

The user terminal updates and saves the obtained current distance from the cell and each neighboring cell and the current position of the synchronization channel window of the cell and each neighboring cell as benchmark information for the next calculation.

Described step B also includes:

When the user terminal finds that the intersection of a certain cell and other cells is not within the intersection range between the cells during the calculation of its location range, the user terminal reselects the cell and obtains the benchmark information of the cell again.

It can be seen from the above-mentioned technical solution provided by the present invention that the present invention uses the added positioning channel or system message to measure the synchronization channels of the current cell and each neighboring cell when the user terminal is idle, and calculate the distance between the current cell and each neighboring cell. TA and ΔTA between base stations. Therefore, when the user terminal is in the IDLE state, the GSM/GT800 user terminal can be accurately positioned without adding external devices, and the positioning accuracy reaches the accuracy of E-OTD.

Description of drawings

FIG. 1 is a schematic structural diagram of an embodiment of a user terminal according to the present invention;

Fig. 2 is the processing flowchart of the embodiment of the method of the present invention;

FIG. 3 is a schematic diagram of obtaining location offset information of the cell according to benchmark information;

Fig. 4 is a schematic diagram of obtaining position offset information of each neighboring cell according to benchmark information of each neighboring cell;

FIG. 5 is a schematic diagram of determining the location range of the user terminal according to the TA(new) between the user terminal and the base station of the cell;

FIG. 6 is a schematic diagram of positioning accuracy of a user terminal based on four base stations;

7 is a schematic diagram of a processing flow after the user terminal is turned on according to the method of the present invention;

Fig. 8 is a schematic diagram of the processing flow of the user terminal cell reselection process according to the method of the present invention.

Detailed ways

The present invention provides a method for locating a user terminal and the user terminal. The core of the present invention is: by adding positioning channels or system messages, increasing the distance information of the TA (the distance information between the user terminal and the base station) of the user terminal in the IDLE state ) tracking, in the case of no interaction between the user terminal and the base station, it can also ensure that the user terminal obtains TA information.

The present invention will be described in detail below in conjunction with the accompanying drawings. The structure of an embodiment of the user terminal of the present invention is shown in Figure 1, including the following modules:

Positioning channel monitoring module: used to monitor the positioning channels of the cell where the user terminal resides and adjacent cells, obtain the current location information of the cell where the user terminal resides and adjacent cells, and pass the obtained location information to the location determination module.

Benchmark information acquisition module: after the user terminal is turned on, through the location update process and cell reselection process of the user terminal, obtain the benchmark information TAn of the cell where the user terminal resides and neighboring cells, the benchmark information TAn includes the user Time advance TA value information between the terminal and the cell where it resides and base stations in neighboring cells. And pass the acquired benchmark information to the benchmark information saving module. The benchmark information acquisition module also uses the current distance information of the local cell and each neighboring cell delivered by the position determination module as the new benchmark information of the local cell and each neighboring cell. The benchmark information includes: the time advance TA value information of the user terminal from the base station of the cell, the cell identifier, the cell distance, and the window position of the cell synchronization channel.

The benchmark information storage module: used to save the benchmark information passed by the benchmark information acquisition module, and pass it to the position determination module and the distance change information acquisition module.

Distance change information acquisition module: used to measure the residence cell of the user terminal and the synchronization channel of the adjacent cell when the user terminal is in the IDLE state, and calculate the distance between the user terminal and the distance in real time based on the benchmark information delivered by the benchmark information storage module The distance change information ΔTAn between the base station of the camped cell and the neighboring cell. And the obtained distance change information ΔTAn is passed to the position determining module.

Position determination module: according to the benchmark information TAn passed by the benchmark information saving module and the distance change information ΔTAn passed by the distance change information acquisition module, determine the current distance between the user terminal and the residential cell and each neighboring cell base station =TAn+ΔTAn. According to the current distance information and the location information of the cell where the user terminal resides and each neighboring cell, the location range information of the user terminal is calculated through a set algorithm. The position determination module also transmits the obtained current distance information between the user terminal and the own cell and each neighboring cell to the benchmark information acquisition module. The position determination module includes: a position calculation module and an information feedback module.

Among them, the location calculation module: according to the current distance information between the user terminal and the cell where the user terminal resides and the base station in the neighboring cell, as well as the location information of the cell where the user terminal resides and the adjacent cell, calculate the location range of the user terminal through a set algorithm information;

Among them, the information feedback module: transmits the obtained current distance information between the user terminal and the cell and each neighboring cell to the benchmark information acquisition module, and the benchmark information acquisition module uses the current distance information as new benchmark information of the cell and each neighboring cell.

Message processing module: used to interact with the cell where the user terminal resides and the base stations of each neighboring cell.

The processing flowchart of the embodiment of the method of the present invention is shown in Figure 2, comprising the following steps:

Step 2-1. Add positioning channel in GT800 system, or add system information in GSM system.

The present invention needs to add a positioning channel in each cell of the GT800 system, and the main functions of the positioning channel are as follows:

In the downlink through the positioning channel, the base station sends the location information of the cell and each neighboring cell to the user terminal, including the cell ID, latitude and longitude and other information of the cell, and notifies the user terminal and the TA value of the cell.

Through the positioning channel in the uplink, the user terminal sends a calibration request message to the base station, and reports the calculated position information of the user terminal.

The above positioning channel can be implemented by adding system messages in other GSM systems except the GT800 system.

Step 2-2. After the user terminal is turned on, perform a location update process to obtain the location benchmark information of the cell, and obtain the location benchmark information of each neighboring cell through the added positioning channel or the RACH channel in the GSM system.

The latitude and longitude information of the base station is determined when the base station is built. The base station sends the geographic location information of the cell to the user terminal through the added positioning channel or system message. Through cell reselection, the user terminal acquires geographic location information of neighboring cells, and stores the geographic location information in its neighboring cell location relationship table.

In the present invention, the processing flow after the user terminal is turned on is shown in FIG. 7 . After the user terminal is turned on, it first performs a location update process, and interacts with the base station where it resides to obtain the CELL-ID and TA values of the cell it resides on.

Then, as shown in FIG. 7 , the user terminal sorts each neighboring cell according to the level and latitude and longitude information of each neighboring cell (cells with the same longitude and latitude are shared base station cells, which do not contribute to positioning and do not reselect). Then, in order to obtain the TA value of each neighboring cell, the user terminal actively initiates the reselection process of each neighboring cell in sequence. After each reselection is completed, the CELL-ID of a certain neighboring cell can be obtained, and then, according to the CELL-ID, send (uplink access Calibration request) message, receive the calibration information returned by the base station of the neighboring cell through the positioning channel or the AGCH channel in the GSM system, and obtain the TA value of the neighboring cell.

As shown in Figure 7, after the reselection process of all cells is completed, the user terminal can obtain information such as the cell ID, latitude and longitude, window position of the synchronization channel, and TA value of the current cell and each neighboring cell. Then, the user terminal returns to the original camping cell. The TA value information of the own cell and each neighboring cell obtained by the user terminal will be used as benchmark information for positioning of the user terminal. The user terminal stores the benchmark information in its memory. The benchmark information is shown in Table 1.

Table 1: Benchmark information of user terminals neighborhood sorting Community ID latitude and longitude The window position of the sync channel TA CELL-ID Frequency BSIC 0 Residence cell ID0 FN0 BSIC-0 X0, Y0 P0 TA0 1 CELL-ID-1 FN1 BSIC-1 X1, Y1 P1 TA1 2 CELL-ID-2 FN2 BSIC-2 X2, Y2 P2 TA2 3 CELL-ID-3 FN3 BSIC-3 X3, Y3 P3 TA3 4 CELL-ID-4 FN4 BSIC-4 X4, Y4 P4 TA4

If part or all of the benchmark information is lost after the user terminal is turned off or powered off, the user terminal re-performs the above-mentioned adjacent cell reselection process after the start-up process is completed. The processing flow of the user terminal cell reselection process in the present invention is shown in FIG. 8 . The specific description is as follows:

In the reselection process, the user terminal can obtain the CELL-ID and TA value of the new camping cell by first interacting with the new camping base station. Then, determine the neighboring areas with TA benchmarks and the neighboring areas without TA benchmarks. For a neighboring cell that already has a TA benchmark, do not reselect to that cell to obtain a TA. For a neighboring cell without a TA benchmark, the user terminal reselects the cell according to the signal level, and obtains the cell-ID, TA and other benchmark information of the cell.

Step 2-3. When the user terminal is in the IDLE state, the obtained benchmark information of the own cell and each neighboring cell is used as a reference, and the TA(new) between the base station of the own cell and each neighboring cell is calculated in real time.

When the user terminal is in the IDLE state after the dedicated channel is occupied. As shown in Figure 7 and Figure 8, firstly, the obtained TA of the cell is used as a benchmark, and during the movement process, the BCCH channel of the resident base station is synchronized, the training sequence is demodulated, and the distance between the user terminal and the resident base station is calculated in real time Change, ie ΔTA. The ΔTA is the location offset information of the cell. Then, TA(new)=TA+ΔTA between the user terminal and the camping base station.

A schematic diagram of obtaining the location offset information of the local cell according to the benchmark information is shown in FIG. 3 . The distance between the user terminal at point A and the base station is TA, and when the user terminal roams to point B, the distance from the base station is TA(new)=TA+ΔTA.

As shown in FIG. 7 and FIG. 8 , in order to achieve more accurate positioning of the user terminal, it is also necessary to calculate ΔTA and TA(new) of each neighboring cell of the user terminal.

According to the above measurement process of the user terminal, the user terminal detects the power level of each neighboring cell in real time in the IDLE state, and synchronizes the system information of each neighboring cell. During the synchronization process, the TAn of the neighboring cell obtained earlier is taken as a benchmark, and the deviation between the current synchronization sequence and the benchmark is confirmed through the synchronization sequence. By measuring the deviation of the demodulated data, the deviation ΔTAn of the TAn value of each adjacent cell can be determined, and the distance TAn(new)=TAn+ΔTAn from each adjacent cell can be obtained. This acquisition process does not require the user terminal to reselect to each neighboring cell.

The user terminal updates and saves the obtained offset-adjusted TA(new) values of the local cell and each neighboring cell and the position of the synchronization channel window as benchmarks for the next calculation.

A schematic diagram of obtaining the position offset information of each neighboring cell based on the benchmark information of each neighboring cell is shown in FIG. 4 .

Step 2-4, when the user terminal is in the IDLE state, determine the position of the user terminal according to the obtained TA(new) between the base stations of the cell and each neighboring cell, and the location information of the cell and each neighboring cell.

As shown in Figure 7 and Figure 8, the user terminal uses a simple algorithm based on the obtained TA(new) between the base station of the cell and each neighboring cell, and the location information such as the latitude and longitude of the cell and each neighboring cell, that is, The location information of the user terminal can be obtained. The calculation method can refer to GSM 0371, which is described as follows:

According to the TA(new) between the user terminal and the base station of the cell, the user terminal can determine that the user terminal is within the range of a circle with a radius of TA(new) and a width of 550m centered on the base station where it resides. As shown in Figure 5. After the user terminal moves from position A to position B, the user terminal is within the range of a circle with a minimum radius of TA and a width of 550 m centered on the base station where it resides. According to the TAn(new) between the base stations of each neighboring cell, it can be determined that the user terminal is within the boundary range between the circles with a radius of TAn(new) and a width of 550m centered on each neighboring cell. As shown in Figure 6.

Fig. 6 is a schematic diagram showing the positioning accuracy of a user terminal based on four base stations. It can be seen from Figure 5 that the positioning accuracy of one base station is a circle of 550 meters, and the positioning accuracy of two base stations is an approximate rhombus with two side lengths of 550 meters; the positioning accuracy of three base stations is an irregular polygon, and the error is 200 meters; 4 base stations can be located in the black area with an error of about 100 meters. The specific implementation is related to the actual environment.

According to the above method, accurate positioning of the user terminal in the IDLE state is realized. Subsequently, the user terminal reports the obtained location information to the base station through a positioning channel or a system message.

In the above-mentioned positioning process for the user terminal, the benchmark information of the cell is very important. If the benchmark of a certain cell is obtained incorrectly, a positioning error will be caused. Therefore, in order to ensure the correctness of the benchmark information, when the user terminal finds that the intersection of a certain cell and other cells is not at the intersection point of most cells during the position calculation process, it is considered that the benchmark of this cell is obtained incorrectly, and the user terminal reselects to The cell initiates a location request to obtain correct benchmark information of the cell.

After the user terminal enters the dedicated channel mode, it can also measure and calculate its current position according to the saved benchmark data of the neighboring cells. At this time, if the user terminal is handed over to a new cell, some benchmark information of neighboring cells will be lost. Because, in the dedicated channel mode, the user terminal cannot reselect to the neighbor cell of the new cell to obtain new benchmark data, which will cause a decrease in positioning accuracy. After the user terminal ends the dedicated channel mode and returns to the IDLE state, it will re-search the benchmark information of the neighbor cell of the new cell to improve the positioning accuracy.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed in the present invention can easily think of changes or Replacement should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (17)

1. A user terminal, comprising: a benchmark information acquisition module, a distance change information acquisition module and a position determination module, wherein: Benchmark information acquisition module: used to obtain the benchmark information of the residential cell and neighboring cells of the user terminal through the location update process and cell reselection process of the user terminal, and pass the acquired benchmark information to the distance change information acquisition module and location determination module; Distance change information acquisition module: used to measure the residence cell of the user terminal and the synchronization channel of the neighboring cell when the user terminal is in the idle IDLE state, and calculate the real-time calculation of the user terminal based on the benchmark information transmitted by the benchmark information acquisition module and the distance change information between the base stations of the residential cell and the neighboring cell, and transfer the obtained distance change information to the position determination module; Position determination module: according to the benchmark information and the distance change information transmitted by the distance change information acquisition module transmitted by the benchmark information acquisition module, determine the current distance between the user terminal and the residential cell and the base station of the neighboring cell, according to the current distance Information and the location information of the residential cell of the user terminal and the adjacent cells, and determine the location range information of the user terminal through calculation. 2. The user terminal according to claim 1, comprising: Positioning channel monitoring module: used to monitor the positioning channels of the cell where the user terminal resides and adjacent cells, obtain the current location information of the cell where the user terminal resides and adjacent cells, and pass the obtained location information to the location determination module. 3. The user terminal according to claim 1, comprising: The benchmark information saving module: used to save the benchmark information acquired by the benchmark information acquisition module, and transmit the saved benchmark information to the position determination module and the distance change information acquisition module. 4. The user terminal according to claim 1, wherein the location determining module comprises: Position calculation module: according to the current distance information between the user terminal and the cell where the user terminal resides and the base station in the neighboring cell, as well as the location information of the cell where the user terminal resides and the adjacent cell, calculate the location range information of the user terminal through a set algorithm; Information feedback module: transmit the obtained current distance information between the user terminal and the cell and each neighboring cell to the benchmark information acquisition module, and the benchmark information acquisition module uses the current distance information as new benchmark information of the cell and each neighboring cell. 5. The user terminal according to claim 1, wherein the benchmark information includes: the time advance TA value information of the user terminal from the base station of the cell, the cell identifier, the cell distance, and the window of the cell synchronization channel Location. 6. A method for locating a user terminal, comprising: A. The user terminal obtains and saves and stores the distance information between the cell and the base station of the adjacent cell; B. When the user terminal is in the idle IDLE state, measure the synchronization channel of the resident cell and the adjacent cell, obtain the distance change information between the resident cell and the base station of the adjacent cell, and change the distance according to the stored distance information and the measurement information to determine the location range of the user terminal. 7. The method according to claim 6, wherein said step A specifically comprises: The user terminal obtains and saves the benchmark information of the cell it resides in and the base station in the neighboring cell. The benchmark information includes: the time advance TA value information of the user terminal from the base station, the cell identifier, the cell distance, and the window of the cell synchronization channel Location. 8. The method according to claim 7, wherein said step A specifically comprises: A1. Add a positioning channel to the trunking communication system; A2. After the user terminal is turned on, it performs a normal location update process to obtain the benchmark information of the cell where it resides. Then, the user terminal initiates a cell reselection process to obtain the benchmark information of each neighboring cell through the positioning channel. 9. The method according to claim 8, characterized in that said step A2 specifically comprises: A21. The user terminal obtains the location information of the cell and each neighboring cell including latitude and longitude information through the positioning channel. The user terminal sorts each neighboring cell according to the level of each neighboring cell, and initiates the reselection process of each neighboring cell in turn. , to obtain the positioning channel description of each neighboring cell; A22. According to the description of the positioning channel, the user terminal enters the positioning channel to send an uplink access calibration request message to the base station of the neighboring cell, receives the calibration information returned by the base station of the neighboring cell through the positioning channel, and obtains the calibration information of the neighboring cell. pole information. 10. The method according to claim 7, wherein said step A specifically comprises: A3. Add system messages in GSM; A4. After the user terminal is powered on, it performs a normal location update process to obtain the benchmark information of the cell where it resides. Then, the user terminal initiates a cell reselection process, and obtains the benchmark information of each neighboring cell through the system message. 11. The method according to claim 10, characterized in that said step A4 specifically comprises: A41. The user terminal obtains the location information of the cell and each neighboring cell including latitude and longitude information through system messages, and the user terminal sorts each neighboring cell according to the level of each neighboring cell, and initiates the reselection process of each neighboring cell in turn , to obtain the system information of each neighboring cell; A42. The user terminal sends an uplink access calibration request message to the neighboring cell base station according to the system message, receives the calibration information returned by the neighboring cell base station, and obtains benchmark information of the neighboring cell. 12. The method according to claim 7, further comprising: When the user terminal loses part or all of the benchmark information, the user terminal will re-select the neighboring cell after the power-on process is completed. Benchmark information, for a cell without a TA benchmark, the user terminal reselects the cell according to the signal level, and obtains the benchmark information of the cell. 13. The method according to claim 6, 7, 8, 9, 10, 11 or 12, characterized in that the step B specifically comprises: When the user terminal is in the IDLE state, based on the obtained benchmark information of the local cell and each neighboring cell, real-time calculation of the distance change information ΔTA between the local cell and each neighboring cell base station, according to the ΔTA and the benchmark information , to determine the distance to the base station of the cell and each neighboring cell, and then determine the location range of the user terminal. 14. The method according to claim 13, characterized in that said step B specifically comprises: B1. When the user terminal is in the IDLE state, the obtained TA of the cell is used as the benchmark. During the movement process, the broadcast control channel BCCH channel of the resident base station is synchronized, the training sequence is demodulated, and the user terminal and the resident base station are calculated in real time. The distance change ΔTA, and then, determine the current distance between the user terminal and the camping base station=TA+ΔTA; B2. The user terminal detects the level of each neighboring cell in real time, takes the TAn of each neighboring cell as a benchmark, and confirms the deviation between the current synchronization sequence and the benchmark through the synchronization sequence, measures the deviation of the demodulation data, and calculates the user in real time The distance change ΔTAn between the terminal and each neighboring base station, and then determine the current distance between the user terminal and each neighboring base station=TAn+ΔTAn; B3. The user terminal determines the location range of the user terminal through calculation according to the obtained current distance from the base station of the cell and each neighboring cell, and the location information of the cell and each adjacent cell. 15. The method according to claim 14, characterized in that the step B3 specifically comprises: According to the current distance between the user terminal and the base station of the cell, the user terminal determines that the user terminal is within a circle with the base station as the center and the minimum radius is the current distance and the width is 550m. For the current distance, it is determined that the user terminal is within the boundary range between circular rings with a minimum radius of the current distance and a width of 550 m centered on each neighboring cell. 16. The method according to claim 13, characterized in that said step B further comprises: The user terminal updates and saves the obtained current distance from the cell and each neighboring cell and the current position of the synchronization channel window of the cell and each neighboring cell as benchmark information for the next calculation. 17. The method according to claim 13, wherein said step B further comprises: When the user terminal finds that the intersection of a certain cell and other cells is not within the intersection range between the cells during the calculation of its location range, the user terminal reselects the cell and obtains the benchmark information of the cell again.

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